When did Australopithecus live? Australopithecus: characteristics, anatomical features, evolution

26.10.201927.05.2017

Australopithecus - extinct bipedal apes; usually regarded as a subfamily of the hominid family. The name proposed for the first find of Australopithecus - the skull of a 3-5 year old calf in South Africa. Skeletal remains of several hundred Australopithecus from South Africa and East Africa (Ethiopia, Kenya, Tanzania) have been found. Australopithecus lived in the period from 4-5 to 1 million years ago. Their appearance is associated with the onset of cooling, when tropical forests began to be gradually replaced by savannahs. Their ancestors were probably some late driopithecus, less adapted to the woody environment and moving to living in more open areas.

african australopithecine

Australopithecus were the first reliable representatives of the evolutionary branch that eventually led to man. Their main distinguishing feature- upright posture (determined by the structure of the pelvis and other bones of the lower limb, as well as by traces in volcanic tuffs) is combined with a monkey brain and a primitive skull. The oldest australopithecines lived in the region of the East African Rift Zone 3-4 million years ago and, probably, have not completely broken the connection with the arboreal way of life. Usually they are referred to as Australopithecus afarensis (after the name of the tectonic depression in Ethiopia where the excavations were carried out). Remains from several dozen individuals of this species are known, including the most complete skeleton of a female (“Lucy”), of which approximately 40% of the bones have been preserved (1974). Many scientists consider Australopithecus Afar as a "transitional link" between the ape and early humans. By appearance it somewhat resembled a "straightened" chimpanzee, but with shorter arms (and fingers) and less developed fangs, an average brain volume of about 400 cc - like that of a chimpanzee. The existence of other, earlier species of australopithecines is also possible, but finds older than 4.5 million years are extremely rare and fragmentary. The early Australopithecus lived in wandering groups scattered over a wide area. Their life expectancy averaged 17-22 years.
Later Australopithecus, which lived from 3 to 1 million years ago, is represented by three species: the miniature (gracil) African Australopithecus (Australopithecus africanus), known mainly from South Africa, as well as two massive Australopithecus: the South African Paranthropus (Paranthropus robustus) and the East African Zinjanthropus ( Zinjanthropus boisei). The latter appeared about 2.5 million years ago and were distinguished by a powerful physique: male individuals could have a growth modern man, women's were significantly smaller. The volume of the brain (on average 500-550 cc) was almost three times less than that of a modern person. These australopithecines are credited with the use of natural objects (animal bones and horns). In later Australopithecus, the tendency to increase the masticatory apparatus prevailed over the tendency to further increase in brain volume.
It is assumed that the most ancient apes of the Australopithecus Afar type could give rise to both late specialized massive Australopithecus, which died out about 1 million years ago, and early representatives of the human genus, which appeared about 2-2.4 million years ago. Usually they are referred to as a skilled person (Homo habilis). In terms of size and general appearance, a skilled man differed little from the classic African Australopithecus, with which he is even united, but had a much larger brain (on average 660 cc) and was able to make rough tools by surface processing of basalt and quartz pebbles.

Introduction

1. general characteristics australopithecines

2. Varieties of Australopithecus

Conclusion

Bibliography

Introduction

The development of the science of the origin of man was constantly stimulated by the search for a "transitional link" between man and ape, more precisely, his ancient ancestor. For a long time, Pithecanthropes ("monkey people") of Indonesia, first discovered by the Dutch doctor E. Dubois in Java at the end of the last century, were considered as such a transitional form. With a completely modern locomotor apparatus, Pithecanthropes had a primitive skull and brain mass, approximately 1.5 times less than that of a modern person of the same height. However, this group of hominids turns out to be rather late. Most of the finds in Java have an antiquity of 0.8 to 0.5 million years ago, and the earliest known authentic Pithecanthropus of the Old World is still no older than 1.6-1.5 million years ago.

On the other hand, it follows from the previous review of the finds of Miocene hominids that representatives of the hominid line of evolution have not yet been identified among them paleontologically. It is obvious that the "transitional link" must be sought at the turn of the Tertiary and Quaternary periods, in the Pliocene and Pliocene epochs. This is the time of the existence of the oldest bipedal hominids of Australopithecus.

Hominids are the most highly organized family of great apes. Includes modern man, his predecessors - paleoanthropes and archanthropes, and, according to most scientists, Australopithecus.

Some scientists limit the family of hominids to only humans themselves, starting with the archanthropes.

Supporters of the extended interpretation of the family include two subfamilies in it: Australopithecus and people proper (Homininae) with one genus man (Homo) and three species - a skilled man (H. habilis), an upright man (H. erectus) and a reasonable man (H. sapiens ).

Of greatest importance for creating a clear idea of the immediate ancestors of the hominid family are the numerous and well-preserved finds in South Africa (the first was made by Raymond Dart in 1924, their number continues to increase). Now in South and East Africa, several fossil species of anthropomorphic primates have been discovered, which are combined into three genera - Australopithecus, paranthropus and plesianthropes - are distinguished into a subfamily or family of Australopithecus.

Of the three possible centers of origin of the original human ancestor (Africa, Asia, Europe), the most complete connection between the Miocene and later hominids can be traced in Africa. There are fairly late Miocene great apes in Asia and Europe, but no very ancient hominids. Thus, Africa is most likely the ancestral home of the hominids.

1. General characteristics of Australopithecus

The history of the study of Australopithecus dates back to 1924, with the discovery of the skull of a 3-5 year old hominoid cub in the South-Eastern Transvaal (now South Africa) near Taung. The fossil hominoid received the name of the African Australopithecus - Avstralopitecus africanus Dagt, 1925 (from "avstralis" - southern). In subsequent years, other locations of South African Australopithecus were discovered - in Sterkfontein, Makapansgat, Swartkrans, Kromdraai. Their remains were usually found in caves: they lay in travertine deposits of carbon dioxide sources flowing from limestones, or directly in the rocks of the dolomite strata. Initially, new finds received independent generic designations - plesianthropus (Plesianthropus), paranthropus (Paranthropus), but, according to modern concepts, only one genus Avstralopithecus stands out among South African Australopithecus with two species: the more ancient ("classical") gracile Australopithecus and the later massive, or paranthropus.

In 1959 Australopithecus have also been found in East Africa. The first discovery was made by the spouses M. and L. Leakey in the oldest layer of the Olduvai Gorge on the outskirts of the Serengeti plateau in Tanzania. This hominoid, represented by a rather theromorphic crested skull, was given the name of East African man, since stone artifacts (Zinjanthropus boisei Leakey) were also discovered in the immediate vicinity. Subsequently, the remains of Australopithecus were found in a number of places in East Africa, concentrated mainly in the region of the East African Rift. Usually they are more or less open sites, including areas of grassy forest-steppe.

To date, the remains of at least 500 individuals are known from the territories of South and East Africa. Australopithecus, apparently, could also be found in other regions of the Old World: for example, the so-called Gigantopithecus from Bilaspur in India or the Javanese meganthrope to some extent resemble massive African Australopithecus. However, the position of these forms of hominoids is not entirely clear. Thus, although the diffusion of Australopithecus into the southern regions of Eurasia cannot be ruled out, their bulk is closely related in their distribution to the African continent, where they are found as far south as Hadar in northeast Africa.

The main part of the finds of East African Australopithecus dates back to the period from 4 to 1 million years ago, but the oldest bipeds, apparently, appeared here even earlier, 5.5-4.5 million years ago.

The Australopithecus were a very peculiar group. They appeared about 6-7 million years ago, and the last of them died out only about 900 thousand years ago, during the existence of much more advanced forms. As far as is known, Australopithecus never left Africa, although some finds made on the island of Java are sometimes attributed to this group.

The complexity of the position of Australopithecus among primates lies in the fact that their structure mosaically combines features that are characteristic of both modern great apes and humans. The Australopithecus skull is similar to that of a chimpanzee. Characterized by large jaws, massive bone ridges for attaching chewing muscles, little brain and a large flattened face. Australopithecus teeth were very large, but the fangs were short, and the details of the structure of the teeth were more human than monkey.

The structure of the Australopithecus skeleton is characterized by a wide low pelvis, relatively long legs and short arms, a grasping hand and a non-grasping foot, and a vertical spine. Such a structure is already almost human, the differences are only in the details of the structure and in small sizes.

The growth of Australopithecus ranged from a meter to one and a half. It is characteristic that the size of the brain was about 350-550 cm³, that is, like that of modern gorillas and chimpanzees. For comparison, the brain of a modern person has a volume of about 1200-1500 cm³. The brain structure of Australopithecus was also very primitive and differed little from that of a chimp. Already at the stage of Australopithecus, the process of losing the coat probably began. Coming out of the shadow of the forests, our ancestor, in the words of the Soviet anthropologist Ya. Ya. Roginsky, found himself in a “warm coat”, which had to be removed as soon as possible.

The way of life of Australopithecus, apparently, was unlike that known among modern primates. They lived in tropical forests and savannahs, feeding mainly on plants. However, later Australopithecus hunted antelopes or took prey from large predators - lions and hyenas.

Australopithecus lived in groups of several individuals and, apparently, constantly roamed the expanses of Africa in search of food. Australopithecus tools were unlikely to be able to manufacture, although they were used for sure. Their hands were very similar to human ones, but the fingers were more curved and narrower. The oldest tools are known from layers in Ethiopia dated 2.7 million years ago, that is, 4 million years after the appearance of Australopithecus. In South Africa, Australopithecus or their immediate descendants used bone fragments to catch termites from termite mounds about 2-1.5 million years ago.

Australopithecus can be divided into three main groups, in each of which several species are distinguished: early australopithecines - existed from 7 to 4 million years ago, had the most primitive structure. There are several genera and species of early Australopithecus. Gracil Australopithecus - existed from 4 to 2.5 million years ago, had a relatively small size and moderate proportions. Massive Australopithecus - existed from 2.5 to 1 million years ago, were very massively built specialized forms with extremely developed jaws, small front and huge back teeth. Let's consider each of them in more detail.

2. Varieties of Australopithecus

The remains of the oldest primates, which can be attributed to the early Australopithecus, were found in the Republic of Chad in Taurus Menalla and named Sahelanthropus tchadensis. The whole skull was given the popular name "Tumai". The dating of the finds is about 6-7 million years ago. More numerous finds in Kenya in Tugen Hills date back to 6 million years ago. They were named Orrorin (Orrorin tugenensis). In Ethiopia, in two localities - Alayla and Aramis - numerous bone remains were found, called Ardipithecus (Ardipithecus ramidus kadabba) (about 5.5 million years ago) and Ardipithecus ramidus ramidus (4.4 million years ago). Finds in two locations in Kenya - Kanapoi and Allia Bay - were named Australopithecus anamensis. They date back to 4 million years ago.

Their growth was not much more than one meter. The brain size was the same as that of a chimpanzee. Early australopithecines lived in wooded or even swampy places, as well as in forest-steppes.

Obviously, it is these creatures that are most suitable for the role of the notorious "intermediate link" between the monkey and man. We know almost nothing about their way of life, but every year the number of finds is growing, and knowledge about environment of that distant time are expanding.

Not much is known about early Australopithecus. Judging by the Sahelanthropus skull, Orrorin femurs, skull fragments, limb bones, and Ardipithecus pelvic remains, early Australopithecus were already upright primates.

However, judging by the bones of the hands of Orrorin and Australopithecus of Anamus, they retained the ability to climb trees or even were four-legged creatures that leaned on the phalanges of the fingers, like modern chimpanzees and gorillas. The structure of the teeth of early australopithecines is intermediate between monkeys and humans. Perhaps even Sahelanthropus were relatives of gorillas, Ardipithecus - the immediate ancestors of modern chimpanzees, and Anaman australopithecines died out without leaving descendants. The history of the description of the Ardipithecus skeleton is the clearest example of scientific integrity. After all, between its discovery - in 1994. and description - at the end of 2009, 15 years have passed!

All these long years, an international group of researchers, including the discoverer, Johannes Haile-Selassie, have been working on preserving crumbling bones, reconstructing a skull crushed into a shapeless lump, describing morphological features and searching for a functional interpretation of the smallest details of the structure of bones.

Scientists did not follow the path of presenting the world with another precocious sensation, but really deeply and carefully studied the most diverse aspects of the find. To do this, scientists had to explore such subtleties of the comparative anatomy of modern great apes and humans, which until now remained unknown. Naturally, data on a variety of fossil primates and australopithecines were also involved in the comparison.

Moreover, the geological conditions of the burial of fossil remains, ancient flora and fauna were considered in the most detailed way, which made it possible to reconstruct the habitat of Ardipithecus more reliably than for many later Australopithecus.

The newly described skeleton of Ardipithecus is a remarkable example of the confirmation of a scientific hypothesis. In his appearance, he perfectly combines the signs of ape and man. In fact, the image that for a century and a half excited the imagination of anthropologists and everyone who cares about our origins has finally become a reality.

Finds in Aramis are numerous - the remains belong to at least 21 individuals, but the most important is the skeleton of an adult female, from which about 45% of the bones remained (more than from the famous "Lucy" - a female Afar australopithecine from Hadar with antiquity 3.2 million years ago ), including almost the entire skull, albeit in an extremely deformed state. The individual had a height of about 1.2 m. and could weigh up to 50kg. Significantly, the sexual dimorphism of Ardipithecus was much less pronounced than in chimpanzees and even later australopithecines, that is, males were not much larger than females. The brain volume reached 300-350 cm³ - the same as in Sahelanthropus, but less than usual in chimpanzees. The structure of the skull is rather primitive. Remarkably, in Ardipithecus, the face and dentition do not have the specialized features found in Australopithecus and modern apes. Based on this feature, it has even been suggested that Ardipithecus could be the common ancestors of humans and chimpanzees, or even only the ancestors of chimpanzees, but upright ancestors. That is, chimpanzees could have bipedal progenitors. However, a more thorough study showed that this probability is still minimal.

The upright posture of Ardipithecus is quite obvious, given the structure of its pelvis (combining, however, ape and human morphology) - wide, but also rather high, elongated. However, such signs as the length of the arms reaching to the knees, the curved phalanges of the fingers, the big toe set far aside and retaining the grasping ability, clearly indicate that these creatures could spend a lot of time in the trees. The authors of the original description emphasize the fact that Ardipithecus lived in fairly closed habitats, with a large number of trees and thickets. In their opinion, such biotopes exclude the classical theory of the formation of bipedal locomotion under conditions of climate cooling and the reduction of tropical forests. O. Lovejoy, based on the weak sexual dimorphism of Ardipithecus, develops his old hypothesis about the development of bipedality on the basis of social and sexual relationships, without direct connection with climatic and geographic conditions. However, the situation can be viewed differently, because approximately the same conditions that were reconstructed for Aramis were assumed by supporters of the hypothesis of the origin of bipedia in the conditions of displacement of forests by savannahs. It is clear that the tropical forests could not disappear instantly, and the monkeys could not master the savanna within one or two generations. It is remarkable that this stage has now been studied in such detail using the example of the Ardipithecus of Aramis.

These creatures could live both in trees and on the ground, climbing branches and walking on two legs, and sometimes, perhaps, down on all fours. Apparently they ate a wide range plants, both shoots with leaves and fruits, avoiding any specialization, which became the key to future human omnivorousness. It is clear that social structure unknown to us, but the small size of the fangs and weak sexual dimorphism indicate a low level of aggression and weak inter-male competition, apparently less excitability, which resulted in millions of years in the ability of modern man to concentrate, learn, carefully, accurately and smoothly perform labor activity, cooperate, coordinate and coordinate their actions with other members of the group. It is these parameters that distinguish a person from a monkey. It is curious that many morphological features of modern apes and humans are apparently based on behavioral features. This applies, for example, to the large jaws of chimpanzees, which are caused not by some specific need for nutrition, but by increased inter-male and intra-group aggressiveness and excitability. It is noteworthy that bonobo pygmy chimpanzees, much friendlier than their common counterparts, have shortened jaws, relatively small fangs, and less pronounced sexual dimorphism.

Based on a comparative study of Ardipithecus, chimpanzees, gorillas and modern people it was concluded that many features of the great apes arose independently.

This applies, for example, to such a specialized feature as moving on bent phalanges of fingers in chimpanzees and gorillas.

Until now, it was believed that a single line of great apes first separated from the line of hominids, which then split into gorillas and chimpanzees.

However, chimpanzees are more similar to Ardipithecus than to gorillas in a number of ways, so the separation of the gorilla lineage must have occurred before the specialization for walking on the phalanges of the fingers appeared, because Ardipithecus does not have it. However, this hypothesis has its weaknesses; if desired, the matter can be presented in another way.

Comparison of Ardipithecus with Sahelanthropus and later Australopithecus once again showed that the evolution of human ancestors was in some jerks.

General level development in Sahelanthropus 6-7 million years ago and Ardipithecus 4.4 million years ago is almost the same, while after only 200 thousand years (4.2 million years ago) the Anamese australopithecines had many new features, which, in turn, were few changed until the time of the appearance of "early Homo" 2.3-2.6 million years ago. Such jumps or turns in evolution were known before, but now we have the opportunity to determine exact time one more of them; you can try to explain them by linking, for example, with climate change.

One of the most surprising conclusions that can be drawn from the study of Ardipithecus is that man, in many ways, differs from the common ancestor with chimpanzees less than a chimpanzee or a gorilla. And this applies, first of all, to the size of the jaws and the structure of the hand and foot - parts of the body, the structural features of which in humans are most often paid attention to.

In Kenya, Tanzania and Ethiopia, fossils of gracile australopithecines called Australopithecus afarensis have been discovered in many locations. This species existed approximately 4 to 2.5 million years ago. The best-known finds are from the Hadar area in the Afar Desert, including a skeleton nicknamed Lucy. Also, in Tanzania, fossilized footprints of erect walking creatures were found in the same layers in which the remains of the Afar australopithecines were found.

In addition to the Afar australopithecines, other species probably lived in East and North Africa in the time interval of 3-3.5 million years ago. In Kenya, a skull and other fossils have been found at Lomekwi, described as Kenyanthropus platyops. In the Republic of Chad, in Koro Toro (East Africa), a single fragment of the jaw, described as Australopithecus bahrelghazali, was found. In South Africa, in a number of localities - Taung, Sterkfontein and Makapansgat - numerous fossils have been found, known as African Australopithecus (Australopithecus africanus). The first find of Australopithecus belonged to this species - the skull of a cub known as Baby from Taung (R. Dart, 1924). African Australopithecus lived from 3.5 to 2.4 million years ago. The latest gracile Australopithecus - dated to about 2.5 million years ago - was discovered in Ethiopia in Bowri and named Australopithecus gari (Australopithecus garhi).

From gracile australopithecines, all parts of the skeleton from many individuals are known, therefore, reconstructions of their appearance and lifestyle are very reliable. Gracil Australopithecus were upright creatures about 1-1.5 meters tall. Their gait was somewhat different from that of a human. Apparently, Australopithecus walked with shorter steps, and the hip joint did not fully extend when walking. Together with enough modern structure legs and pelvis, the arms of Australopithecus were somewhat elongated, and the fingers were adapted for climbing trees, but these signs can only be a legacy from ancient ancestors.

During the day, Australopithecus roamed the savannah or forests, along the banks of rivers and lakes, and in the evening they climbed trees, as modern chimpanzees do. Australopithecus lived in small herds or families and were able to travel quite long distances. They ate mainly plant foods, and they usually did not make tools, although not far from the bones of Australopithecus gari, scientists found stone tools and antelope bones crushed by them. Also, for the South African Australopithecus (Makapansgat Cave), R. Dart put forward a hypothesis of osteodontokeratic (literally - “bone-dental-horn”) culture. It was assumed that Australopithecus used the bones, horns and teeth of animals as tools. Later studies have shown that most of the wear marks on these bones are the result of gnawing from hyenas and other predators.

Like the early members of the genus, the gracile australopithecines had an ape-like skull that matched the almost modern rest of the skeleton. The Australopithecus brain was similar to that of a monkey in both size and shape. However, the ratio of brain mass to body mass in these primates was intermediate between a small simian and a very large human.

Approximately 2.5-2.7 million years ago, new species of hominids arose, which had a large brain and were already attributed to the genus Homo. However, there was another group of late Australopithecus that deviated from the line leading to man - the massive Australopithecus.

The oldest massive australopithecines are known from Kenya and Ethiopia - Lokalei and Omo. They have dates about 2.5 million years ago and are called Ethiopian Paranthropus (Paranthropus aethiopicus). Later massive australopithecines from East Africa - Olduvai, Koobi-Fora - dating from 2.5 to 1 million years ago are described as Paranthropus Boys (Paranthropus boisei). In South Africa - Swartkrans, Kromdraai, Dreamolen Cave - massive Paranthropus (Paranthropus robustus) are known. The massive Paranthropus was the second species of Australopithecus to be discovered.

When examining the skull of Paranthropus, huge jaws and large bone ridges are striking, which served to attach the chewing muscles. The jaw apparatus reached its maximum development in East African Paranthropus. The first open skull of this species, due to the size of the teeth, even received the nickname "The Nutcracker".

Paranthropes were large - up to 70 kg in weight - specialized herbivorous creatures that lived along the banks of rivers and lakes in dense thickets. Their way of life was somewhat reminiscent of the way of life of modern gorillas. However, they retained their bipedal gait and may even have been able to make tools. In layers with paranthropes, stone tools and bone fragments were found, with which hominids tore up termite mounds. Also, the hand of these primates was adapted for the manufacture and use of tools.

The paranthropes "made a bet" on size and herbivory. This led them to ecological specialization and extinction. However, in the same layers with paranthropes, the remains of the first representatives of hominins - the so-called "early Homo" - more progressive hominids with a large brain, were found.

Conclusion

As studies of recent decades have shown, Australopithecus were the immediate evolutionary predecessors of man. It was from among the progressive representatives of these two-legged fossil primates that about three million years ago, creatures emerged in East Africa who made the first artificial tools, created the oldest Paleolithic culture - the Olduvai, and thereby laid the foundation for the human race.

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2. Varieties of Australopithecus

Their growth was not much more than one meter. The brain size was the same as that of a chimpanzee. Early australopithecines lived in wooded or even swampy places, as well as in forest-steppes.

These creatures could live both in trees and on the ground, climbing branches and walking on two legs, and sometimes, perhaps, down on all fours. They apparently fed on a wide range of plants, both shoots with leaves and fruits, avoiding any specialization, which became the key to future human omnivorousness. It is clear that the social structure is unknown to us, but the small size of the fangs and weak sexual dimorphism indicate a low level of aggression and weak inter-male competition, apparently less excitability, which resulted after millions of years in the ability of a modern person to concentrate, learn, carefully, accurately and smoothly perform work activities, cooperate, coordinate and coordinate their actions with other members of the group. It is these parameters that distinguish a person from a monkey. It is curious that many morphological features of modern apes and humans are apparently based on behavioral features. This applies, for example, to the large jaws of chimpanzees, which are caused not by some specific need for nutrition, but by increased inter-male and intra-group aggressiveness and excitability. It is noteworthy that bonobo pygmy chimpanzees, much friendlier than their common counterparts, have shortened jaws, relatively small fangs, and less pronounced sexual dimorphism.

Based on a comparative study of Ardipithecus, chimpanzees, gorillas and modern humans, it was concluded that many features of great apes arose independently.

This applies, for example, to such a specialized feature as moving on bent phalanges of fingers in chimpanzees and gorillas.

Until now, it was believed that a single line of great apes first separated from the line of hominids, which then split into gorillas and chimpanzees.

Comparison of Ardipithecus with Sahelanthropus and later Australopithecus once again showed that the evolution of human ancestors was in some jerks.

The general level of development in Sahelanthropus 6-7 million years ago and Ardipithecus 4.4 million years ago is almost the same, while after only 200 thousand years (4.2 million years ago), the Anaman australopithecines developed many new features, which, in turn, , changed little until the time of the appearance of "early Homo" 2.3-2.6 million years ago. Such jumps or turns of evolution were known before, but now we have the opportunity to determine the exact time of one more of them; one can try to explain them by linking them, for example, with climate change.

From gracile australopithecines, all parts of the skeleton from many individuals are known, therefore, reconstructions of their appearance and lifestyle are very reliable. Gracil Australopithecus were upright creatures about 1-1.5 meters tall. Their gait was somewhat different from that of a human. Apparently, Australopithecus walked with shorter steps, and the hip joint did not fully extend when walking. Together with a fairly modern structure of the legs and pelvis, the arms of Australopithecus were somewhat elongated, and the fingers were adapted for climbing trees, but these signs can only be a legacy from ancient ancestors.